America's dependence on foreign sources of fuel oil has resulted in significant political and economic problems in recent years. As a result, great efforts have been made to find a cheaper and more reliable domestic energy alternative. One such alternative is natural gas which is domestically available, plentiful, relatively inexpensive and environmentally safe as compared to oil. Because one of the largest uses for oil is as a fuel for motor vehicles, great strides have been made to develop alternative fuels including natural gas.
One possibility is a dual-fuel modified diesel engine which runs on a 60/40 diesel fuel to LNG mixture. While this engine substantially reduces diesel fuel consumption, it requires that LNG be delivered to the engine at approximately 300 psi, a pressure approximately 6 times the normal storage pressure for LNG. Other natural gas powered engines require that the LNG be delivered at pressures ranging from less than 50 psi to more than 500 psi. Therefore, a LNG fueling station that can deliver LNG to vehicles having wide variations in delivery pressure requirements is desired. Moreover, fueling must be accomplished such that when the filling operation is completed the pressure of the vehicle's filled tank is at least as high as the minimum operating pressure of the vehicle, but less than the venting pressure of the tank.
Moreover, LNG is an extremely volatile substance that is greatly affected by changes in pressure and temperature. As a result, the fueling station must be able to accommodate fluctuations in pressure and temperature and transitions between the liquid and gas states resulting from heat inclusion that invariably occurs in cryogenic systems. Optimally, the fueling station should be able to meet these conditions without venting LNG to the atmosphere because the venting of LNG is wasteful and potentially dangerous.
Thus a no loss LNG fueling station that is efficient, safe and can deliver LNG at a range of temperatures, pressures and operating conditions is desired.